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The presence of higher current harmonics has a negative impact on the efficiency and reliability of the elements of network. Higher current harmonics can lead to significant increases of resistance, voltage drop and active losses in busbar, also to decreasing network power factor. Existing engineering techniques can’t provide a reliable calculation of the parameters of busbars at higher current harmonics influences. Therefore, the aim of the work is to develop a new approach of parameters determination and the voltage drop estimation in busbar at higher current harmonics influence. Mathematical model of electromagnetic processes in busbar, which takes into account their design features, non-linearity of magnetic and electrophysical properties, proximity effects, surface and external surface effects, was developed and proposed. This model will allow to determinate the components of active and reactive resistances of busbar, voltage drops for each eigenvalue of the amplitude and frequency of current harmonics. Based on field simulation results was obtained the functional dependence in bicubic polynomial form. For effective spectra and amplitudes of higher harmonics, at selecting the corresponding polynomial coefficients, it will allow to determinate the components and the resulting values of voltage drops for an individual busbar’s design without spending time on field simulation. Based on the proposed approach, a method will be developed for the busbar's parameters identification and voltage drop estimation. This will allow effectively define the network configuration, installed capacity of compensating devices, which will provide the reliability of electrical collectors with the declared technical data and etc.

The work is d to improving methods for calculating the cooling system of a microturbine with a rotor on air bearings. When designing gas turbines, it is important to integrate gas-dynamic calculations with thermal finite-element calculations. In practice, the conjugation of temperature fields in solids and liquids, as well as the transfer of thermal loads between the media are carried out using several approaches: direct, non-conjugate and sequential coupled. Numerical simulation of the coupled heat transfer in a cavity formed by the gap between the rotor and stator is carried out. To calculate the flow characteristics of a viscous compressible fluid and heat transfer. The degree of influence on the results of the type of turbulence model used, the influence of taking into account the conjugate heat transfer, is studied. The effect of the mass flow rate of the cooler on the flow structure and the cooling efficiency of the walls of the rotor and stator is investigated. A comparison is made with experimental data. Numerical experiments have shown that in typical cases the flow in the cavity is turbulent. The cooling efficiency has a limit on the flow rate of the cooler. The temperature distribution along the length of the rotor has a noticeable minimum in the region of the middle of the length of the rotor. The significance of the obtained results lies in the fact that the choice of the turbulence model weakly affects the calculation results and taking into account the conjugate nature of heat transfer is necessary.